358 DISEASES OF SWINE 



been thoroughly heated in a dry oven so as to destroy all possible 

 germ contamination. This is the serum blood, and to this is added 

 a small percentage of 5 per cent, carbohc acid solution. This is 

 usually added in the proportion of 1 part of carbolic acid solution 

 to 9 parts of blood; that is to say, 100 c.c. of carbolic solution is 

 added to 900 c.c. of blood. This gives a solution which contains 

 I of 1 per cent of carbolic acid. 



We now have the complete hog-cholera serum. It is not, in 

 reality, a serum at all, but merely a defibrinated blood taken from 

 the body of a hog that has been hyperimmunized one week before 

 with an enormous dose of hog-cholera virus. This blood contains 

 an enormous number of germ fighters or antibodies, and it is to the 

 presence of these antibodies that it owes its real disease-preventing 

 properties. 



The addition of carbolic acid in sufficient amount to give a 

 ^ of 1 per cent, solution is for the purpose of preventing growth 

 of any germs that may be present, and in this manner keep 

 the serum from spoiling. The carbolic acid is not added for any 

 beneficial effect that it might have in the treatment of cholera. 



This serum is now placed in large dark-colored bottles, which are 

 tightly stoppered and placed in a dark, cool cellar, where they are 

 kept at a temperature of 50° F. or lower. This also prevents in 

 large measure the growth of any bacteria. The serum is kept in 

 these large storage bottles until it is intended for shipment to the 

 field, when it is brought out and bottled into smaller glass-stoppered 

 bottles. These are sealed over with paraffin or wax and sent out 

 immediately. 



These serum shipments should be made by as rapid a route as 

 possible, and arrangements should be made to receive same im- 

 mediately upon its arrival. It should then be placed in a cool 

 place and kept there until ready for use. This is very important, 

 as serum spoils very quickly if it is allowed to get warm and remain 

 that way for any length or time. 



In the process of manufacture every effort possible is made to 

 keep all germs out of the serum, but even with the utmost care a 

 few germs are bound to enter. It is not possible to boil the serum 

 without destroying the antibodies to which it owes its value. Ac- 

 cordingly, these germs cannot be killed, but must be allowed to 



